GAS ASSIST INJECTION MOLD

摘要

PURPOSE:To prevent gas from flowing backward to a molten resin injection port at the time of the injection of the gas in a gas assist injection molding method. CONSTITUTION:A cavity 12 is formed in a mold 10 and a gate 14 and a molten resin injection port 16 are allowed to communicate with each other by a runner 18. The runner 18 consists of the first runner 20 extending into the mold 10 from a molten resin injection port 16 and the second runner 22 extending to the cavity 12 from the end part of the first runner 20. The mold 10 has a chamber 24 whose cross section is circular in the extending direction of the first runner 20. A plunger 30 has the bottom part 32 slid with a large diameter part 26 and the gas nozzle part 34 slid with a small diameter part 28. The plunger 30 has the gas passage 38 extending to the gas nozzle part 34 from the bottom part 32 and also extending in the radial direction thereof in the vicinity of the leading end of the gas nozzle part 34. A gas injection plug 40 allows the outside of the mold 10 to communicate with the chamber 24.